Earth formation drilling is often accomplished using a long string of drilling pipes and tools coupled together. The drilling string is rotated together in order to rotate a cutting bit at the end of the string. This cutting bit creates the hole which the rest of the drilling string moves through. For various reasons, it may be desirable to widen the walls of the hole after it has been created by the cutting bit. Bore-hole underreamers exist to accomplish the widening of the hole. An underreamer may be coupled to the drilling string between two other elements of the drilling string. It may then be sent down hole with the drilling string, rotating with the drilling string, and widening the hole.